SignalHub-Storm nearing Carolinas threatens area with up to 10 inches of rain, possible flooding

North and SignalHubSouth Carolina are bracing for heavy wind, rain, possible floods and tornadoes as a potential tropical system was set to arrive on Monday.

As of Monday morning, the "low-pressure system" did not yet classify as a tropical storm, the National Hurricane Center said, but it picked up some strength on its path northwest toward South Carolina's coast and its speed increased to 5 mph. At around 100 miles east of Charleston, it carried maximum sustained winds of 50 mph.

The storm is expected to move through the Carolinas beginning Monday afternoon through Wednesday, according to an advisory Monday morning.

If it becomes a tropical storm, it will be named Helene – the next name on the list. The chances of that have lessened as the storm's structure became less organized in the early hours of Monday, and its maximum winds are expected to slow down as it approaches the coast, forecasters say.

A tropical storm warning was in effect for a 300-mile strip of coastline across both states on Monday morning, and the area was expected to see "gusty winds, heavy rains and coastal flooding," according to the National Hurricane Center. An earlier tropical storm warning for a 100-mile stretch of South Carolina's coast to the south was discontinued at 11 a.m.

The storm is expected to drench the hardest-hit area in up to 8 inches of rain, while some spots could see as much as 10 inches of rain, according to the advisory. "A couple" tornadoes could also spin up in the eastern parts of both states through Monday night, the center said.

The rainfall could trigger "locally considerable flash and urban flooding" in the Carolinas and put the entire Mid-Atlantic region at risk of isolated floods, according to the advisory. Rivers in southeastern North Carolina and northeastern South Carolina could also experience minor flooding through Monday night.

More:Tropical storm tracker: Cyclone in Atlantic could hit Carolinas Monday

Latest developments:

∎ The National Hurricane Center said the storm is expected to gain little strength before it makes landfall. It will weaken further as it moves inland until it dissipates on Wednesday, forecasters said.

∎ Elevated tides associated with the full moon, large swells and strong northeast winds are forecast to cause high tides along the coast leading to minor or moderate coastal flooding through early in the week, the weather service said. Additional storm development could also further increase the risk of more significant coastal flooding.

∎ Gordon lost ferocity out in the Atlantic and weakened to a tropical depression by 5 p.m., according to the National Hurricane Center. Gordon posed no threat to land, the weather service added.

More:Firefighters make progress in battling Southern California wildfires amid cooler weather

Tropical storm or not, 'impacts will be the same'

Although the storm's maximum sustained wind exceeds the 39 mph required for it to be classified a tropical storm, its center is too divided.

"It doesn't have a very defined center right now," AccuWeather lead hurricane expert Alex DaSilva said. In order to become a tropical storm, "it will need to essentially form a closed center of circulation," he said. He estimated the likelihood of that at around 70% on Monday morning.

Still, whether or not it becomes a tropical storm and is named, "the impacts will be the same," DaSilva said.

Those include possible dangerous flash floods from the heavy overnight rain expected from the Southeast to the Mid-Atlantic and winds traveling up to 60 mph in the Carolinas, according to DaSilva. Although not widespread, "there could be some power outages, some trees down," he said.

Tornadoes could pop up overnight, he said. "These tornadoes can develop very quickly, which can make them extra dangerous."

The storm could also cause erosion to the local beach – already vulnerable after Hurricane Debby battered the area last month. "The coastline is already kind of weakened by previous storms, so it's not going to take a whole lot to cause some pretty significant issues there," DaSilva said.

'Homegrown' storms spin up close to coastline

The storm system is "homegrown," meaning it formed quickly close to the coast, like most storms and hurricanes that hit the U.S. every year, according to Weather.com meteorologist Jonathan Erdman.

It's much rarer for hurricanes to form far out into the Atlantic before making landfall – just 10 of the 55 hurricanes that impacted the U.S. from 1995 to 2023 formed in the Atlantic between the Lesser Antilles and Africa, he wrote.

"Homegrown" storms can pose a greater threat, since they form close by, according to Weather.com. They are more common in the early part of the hurricane season, which stretches from the beginning of June through the end of November.

North Carolina coast gets more than 15 inches of rain

As the storm approaches, some spots in New Hanover County, North Carolina, have picked up more than a foot of rain since midnight on Monday, according to the National Weather Service. Carolina Beach, around 12 miles south of Wilmington, was drenched in more than 15 inches of rain.

In a post to X, the weather service warned of "considerable flash flooding," expected to worsen in Brunswick County, to the west.

Some North Carolina schools close

With the potential for tropical storm conditions on Monday, some schools in North Carolina will not open.

Brunswick County Schools posted on Facebook on Monday morning that students should stay home, while teachers have an optional workday.

Meanwhile, Brunswick Community College will also shutter its doors on Monday because of the severe weather. Classes will take place remotely where possible. 

Students in Bladen, Columbus and Whiteville counties will also attend school remotely.

Schools in New Hanover will release students two hours early because of the weather and "street flooding," according to a Facebook post. Pender County schools will operate on a normal schedule.

-- Sherry Jones, Wilmington StarNews

Risk for swimmers on Outer Banks of North Carolina

The Outer Banks of North Carolina is known for currents that can be dangerous for swimmers. The new system heightened the risk, the weather service said in an update Sunday.

The good news: The most likely time for strong rip currents to occur Sunday was a couple of hours on either side of low tide, which took place before noon. Still, the risk of rip currents remained, and the update warned inexperienced swimmers to stay out of the water.

"Rip currents can sweep even the best swimmers away from shore into deeper water," the update warned. "Dangerous shore break can throw a swimmer or surfer head first into the bottom causing neck and back injuries."

Contributing: John Bacon and Thao Nguyen, USA TODAY